Beyond Sag: Fine-Tuning Fork Air Spring and Volume Spacers

Setting sag is only the beginning of fork setup. Volume spacers change the air spring's ramp-up, which affects bottom-out resistance and mid-stroke support.

Start with sag Set sag at about 15-20 percent in riding kit, then use a zip-tie or the fork's O-ring to measure travel used on a ride.

Adjust volume If you use full travel too often on small hits, add volume spacers to make the spring more progressive. If you never use the last bit of travel, remove a spacer. Forks such as the Fox Float 36 Factory and RockShox Lyrik Ultimate offer simple spacer systems.

Damping Set rebound so the fork returns quickly but does not buck. Adjust compression for support in corners and under braking.

One change at a time Change one setting at a time and ride the same trail to feel the difference. Keep notes so you can return to a known baseline.

Change one thing at a time Adjust air pressure first, then add or remove a volume spacer and ride the same section to judge the change. A progressive fork resists bottoming out harder, while a more linear one uses its travel more easily. Record each setting so you can return to a good baseline.

Use the right lubricant in the right place Chain lube, suspension grease, assembly paste and brake fluid are not interchangeable. Using the wrong product can attract dirt, degrade seals or contaminate brakes. Check the manufacturer's recommendation for each part and apply sparingly, wiping away any excess.

Check consumables regularly Brake pads, chains, tyres, cables and sealant all wear out. Inspect them on a regular schedule and replace them before they fail. Replacing a worn part early is almost always cheaper than repairing the damage a failed one can cause.

Tools and preparation Gather everything you need before you start: the right tools, a torque wrench, a clean workspace, a bike stand if you have one and the manufacturer's instructions. Working methodically and tightening bolts to the specified torque prevents damage and makes the job far less stressful.

Safety first Brakes, bolts and steering parts are safety-critical. After any work, check that everything is tight and moves correctly, test the brakes before you move, and take a short, gentle ride before attempting a full trail. If anything feels wrong, stop and investigate.

How often to do it Maintenance intervals depend on how and where you ride. Wet, muddy or dusty conditions, long rides and heavier riders or e-bikes all wear components faster. Use the manufacturer's guidance as a baseline and shorten the intervals if your conditions are harsh.

Keep a maintenance log Record dates, pressures, settings and parts replaced. A simple log helps you spot wear patterns, plan servicing before parts fail and return to a setup that worked well. It also makes warranty claims and resale easier.

Common mistakes to avoid The most common errors are over-tightening bolts, mixing incompatible fluids or lubricants, skipping the manual and ignoring small problems until they become large ones. Slow down, read the instructions and check each step before moving to the next.

Also consider

• Fox 38 Factory GRIP2 (Fox Racing Shox): £933, rated 4.9. Long-travel enduro fork with 38mm stanchions and quad-adjustable GRIP2 damper.
• Fox Float 38 Factory (Fox): £971, rated 4.9. Burly enduro fork with GRIP2 damper and 38mm stanchions.
• Fox 40 Factory (Fox): £1,120, rated 4.9. Dual-crown downhill fork that has been a mainstay at World Cup level.